The present invention relates to a circuit card retention mechanism, and more particularly, to a retention mechanism that secures an electrical connector on a printed circuit card to an electrical connector mounted on a main circuit board.
Today, printed circuit cards are used in many electronic devices, such as computers and telecommunications equipment. In these devices, printed circuit cards are often electrically connected to a main circuit board using connectors extending from the printed circuit card and mating with connectors located on the main circuit board.
In conventional personal computers (PC""s), for example, the main circuit board is generally referred to as the motherboard. The electrical connector located on the motherboard in a PC is generally referred to as a card slot and can receive a variety of printed circuit cards that support, among other things, video displays, serial interface ports, parallel interface ports, computer memory (RAM) and additional data storage. Many of the printed circuit cards provide inputs and outputs disposed generally on one or more sides of the printed circuit card for connection to external equipment as well as other components internal to the electronic device. Indicator lamps and displays are often disposed on an external face of the printed circuit card to indicate equipment status.
In PC equipment, the printed circuit card electrically mates with the main circuit board when it is installed in a card slot with the printed circuit card connector mated to the main circuit board connector. Printed circuit cards are usually held in place with a fastener, such as a screw, installed at one end of the card. Even with this fastener, printed circuit cards are sensitive to motion and a small degree of motion can dislodge a card and result in an equipment malfunction.
Although a manufacturer tests the equipment prior to shipping, cards may partially dislodge during shipping and handling and result in a subsequent malfunction. The loss of electrical contact that results from partially dislodged cards is often difficult to diagnose because only some of the electrical contacts between the printed circuit card and the main circuit board are lost. Thus, connection between the circuit card and the main circuit board is not completely lost but only impaired, which can be difficult to diagnose. This often leads to calls from dissatisfied customers requesting manufacturer assistance in debugging equipment failures. This extended involvement with the customer increases manufacturer costs and decreases customer confidence in the underlying equipment.
Several patents have issued in an attempt to cope with some of these problems. For example, U.S. Pat. No. 5,603,628, issued to Schapiro, Jr. on Feb. 18, 1997, relates to a retainer for printed circuit cards that combines a set of anchors located on both sides of a connector and an adjustable tie-means, (i.e., tie-wrap), that extends around both sides of the card and engages the connector to secure the card to the connector. The adjustable tie-means allows the retainer to be used with cards of different height. However, because the tie-means extends over both sides of the printed circuit card, it invariably rests on the various printed circuit card components that are necessary for the proper functioning of the card. As a result, repeated connection and disconnection of the tie means may damage the card.
Another example, U.S. Pat. No. 5,650,917, issued to Hsu on Jul. 22, 1997, relates to a Central Processing Unit (CPU) mounting structure that includes a U-shaped mounting frame mounted on an electrical connector that receives a CPU card. The CPU card is held in the U-shaped mounting frame by two holding down devices, i.e., screws. The mounting structure, which is intended for use with CPUs, makes unusable a sizeable amount of space on the circuit board as the U-shaped structure extends on three sides of the board. The U-shaped structure also does not allow interface access to the printed circuit card on the sides.
Yet another example, U.S. Pat. No. 4,826,447, issued to Forker et al. on May 2, 1989, relates to a retainer for locking a printed circuit board with an edge connector that is directly soldered to the conductive paths on a second circuit board. The circuit board is permanently connected to the connector and is removable only after disengaging the retainer and de-soldering the electrical connections to the second circuit board. The retainer, which does not allow interface access to the printed circuit card on the sides, requires a large surface area of potentially usable circuit board space.
Thus, there is a need for a sturdy and reliable printed circuit card retention mechanism that is easy to engage and disengage and does not require de-soldering of connections. There is a further need for a printed circuit card retention mechanism that does not damage the printed circuit card when the retention mechanism is engaged and disengaged. There is yet a further need for a printed circuit card retention mechanism that occupies a minimum of the usable surface area on the printed circuit card and allows for access to connectors on all four sides of the printed circuit card.
Accordingly, the present invention is directed to a retention mechanism for securing an electrical connector on a printed circuit card to an electrical connector mounted on a main circuit board. The retention mechanism is constructed having a base with at least one snaplet, to secure the retention mechanism to the electrical connector of the main circuit board, and at least one guiding ledge, to support the connection point between the main body of the printed circuit card and the electrical connector of the printed circuit card. The retention mechanism is also constructed having a locking feature, which secures the printed circuit card to the electrical connector of the main circuit board, by fitting into a slot between a card arm and a main portion of the printed circuit board.
The present invention and its features and advantages will become more apparent from the following detailed description with reference to the accompanying drawings.